1. Field of the Invention
The present invention relates to a motor of a reciprocating compressor, and more particularly, to a coil winding number variable type motor that is capable of controlling a stroke by varying the number of windings of motor coil by itself, and a coil winding number varying method for varying cooling and heating capacity of a reciprocating compressor
2. Description of the Background Art
FIG. 1 is a schematic block diagram showing the construction of an operation control apparatus of a reciprocating compressor in accordance with a conventional art.
As shown in FIG. 1, the operation control apparatus includes a reciprocating compressor 10A for controlling a cooling capacity by varying a stroke through a linear movement of a piston (not shown), an electricity circuit unit 10 with a ground terminal connected between a current sensing resistance R1 and an AC switching device, that is, a triac (Tr1), and supplying a voltage and a current to the reciprocating compressor 10A according to a switching signal of the triac (Tr1); a current detector 20 for detecting a current applied to the reciprocating compressor 10A on the basis of the ground terminal and outputting the detected current; a voltage detector 30 for detecting a voltage applied to the reciprocating compressor 10A on the basis of the ground terminal, and outputting the detected voltage, computing a stroke, and inputting a switching signal for controlling the voltage applied to the reciprocating compressor 10A to the triac (Tr1), so as for the stroke to follow an initial stroke reference value.
The operation of the operation control apparatus of a reciprocating compressor constructed as described above will now be explained with reference to the accompanying drawings.
First, in the reciprocating compressor 10A, an internal piston performs a linear reciprocal movement by a stroke voltage according to an initial stroke reference value set by a user, and accordingly, the stroke is varied and cooling capacity of a refrigerator or an air-conditioner is varied according to the varied stroke.
A Turn-On period of the triac is lengthened by the switching control signal of the microcomputer 40, and accordingly the stroke is increased. At this time, a voltage and a current generated from the reciprocating compressor 10A are detected by the voltage detector 30 and the current detector 20 and applied to the microcomputer 40.
Then, the microcomputer 40 computes a stroke by using the voltage and the current detected by the voltage detector 30 and the current detector 20, compares the computed stroke with the initially applied stroke reference value, and outputs a switching control signal accordingly.
That is, if the computed stroke is smaller than the initial stroke reference value, the microcomputer 40 outputs a switching control signal for lengthening an ON period of the triac (Tr1), to thereby increase the stroke voltage applied to the reciprocating compressor 10A.
If, however, the computed stroke is greater than the initially applied stroke reference value, the microcomputer outputs a switching control signal for shortening the ON period of the triac (Tr1), to reduce the stroke voltage applied to the reciprocating compressor 10A.
In the motor of the reciprocating compressor 10A, an internal coil is wound in a predetermined number and driven by the stroke voltage.
Accordingly, the operation control apparatus of a reciprocating compressor of the conventional art controls the ON/OFF period of the triac and accordingly performs a stroke control, to thereby cope with the load and the voltage change.
However, the conventional operation control apparatus of a reciprocating compressor has the following problems.
That is, in order to control the stroke, since the driving voltage applied to the motor of the reciprocating compressor is controlled by varying the ON/OFF period of the switching signal inputted to the triac, a noise is generated according to switching, a circuit such as a noise filter is additionally required to cancel the noise, resulting in that its expense is increased.
In addition, in case that the stroke is controlled by varying the ON/OFF period of the triac by switching, a power factor is influenced due to a harmonic wave, for which a circuit is additionally required, also resulting in that the expense is increased.
Moreover, due to a surge voltage (a voltage which is instantly increased), the triac is broken down, and due to the harmonic wave component generated by the triac, an efficiency of the reciprocating compressor is degraded.